Question

Quinine (C2H2N,O,) is the most important alkaloid derived from cinchona bark. It is used as an antimalarial drug. For quinine pk. = 5.1 and PK 1900.0 mL of water. Calculate the pH of saturated aqueous solution of quinine. Consider only the reaction Q + H,0 = QH+ + OH- described by = 9.7 (pKb = -log(K)). Only 1.0 g of quinine will dissolve in here Q = quinine.

Answer 1

. Page x)First calculate the concentration 8 awnine Ig quinine x lmolquinine 324.417 g .. 9000L . in = 1.62 x 10-30 *)Next, set up an ICE (Initial, change, equilibrium) - table for the problem. * a oh oh initial 1.62 x 103 moo change = -x+x+x " Equilibrium = 1162 x 103 m-XXX * By using the Kb equation 1 ks = [OH-] [ant] [a] 7.94 X106 = x² 7.94 X10 = 7.62x10 3 x AKT

page=2 using the quadratic egunetion to solve for you - b = db²-4ac 20 , =-(-7.94 X169) I JC7-24 X109) 24651.62x10 $4.40335 X = 1.108 104 E (OH) = 110x104 TIMMT MIT MIT MINIMITIVAM * use the hydrolde concentration to calculate the pot and then the pH - pott =- log (OH) pot = -log (1.10X104) . . . poh = 3.96 pH = 14.0-pot. pH = 14.0-3.96. O-POH ENT pH = 10.04